Project Summary Deficits in cognitive control are at the core of many functional declines in healthy older adults. A fundamental contributor to these deficits is compromised regulation of both external and internal attention processes, which leads to a decreased ability to effectively engage in complex, goal-directed behavior. As a result, there is a critical need to develop targeted interventions to reverse or prevent declines in regulation of attention processes in healthy older adults. Targeted cognitive training and focused-attention meditation are two interventions that hold great promise for boosting attention and cognitive control abilities in healthy older adults, but we lack a firm understanding of the neural and physiological mechanisms that underlie this positive neuroplasticity. We also know little about whether such interventions might have multiplicative effects on cognition when administered in a combinatorial manner. The goals of the proposed research are threefold. First, we will determine the unique and synergistic effects of an externally-oriented attention training paradigm and an internally-oriental meditation paradigm on enhancing regulation of external and internal attention in healthy older adults, leading to improvements in functional outcomes. Second, we will examine the impact of potential genetic, physiological, and social moderators of the treatment effects in individuals and subgroups who show variability in their response to the interventions. Third, we will document the neural and physiological mechanisms underlying the unique and synergistic plasticity associated with each individual or combined intervention. To accomplish these aims, we will conduct a randomized clinical trial in healthy older adults of two novel cognitive training paradigms that are deployed on wireless mobile devices. We will collect data from two samples: a large (N = 1650) sample that will be recruited nationally who will complete the study entirely on mobile devices and a smaller (N = 225) local sample who will also complete more in-depth lab-based cognitive assessments, EEG, structural MRI, and functional MRI. The national sample will provide the numbers needed to examine individual and subgroup differences in treatment response in an extremely diverse sampling of the general population. The local sample will allow us to dive deeper into the underlying neural and physiological mechanisms that give rise to training effects. Both groups will complete baseline, immediate follow-up, and one-year follow-up assessments of cognitive and functional outcomes, while the local group will undergo neuroimaging at all three time points. We anticipate that the unique methodological approach and experimental design will significantly advance the development of rehabilitation programs directed at the broad range of cognitive abilities and functional outcomes in both healthy and clinical populations that suffer from problematic regulation of attention and cognitive control.